Corrado Passera, who also previously served as chief executive of Intesa Sanpaolo, is working with a series of private equity firms including U.S. buyout fund Warburg Pincus on a plan that includes a reserved capital increase of between 2 billion to 2.5 billion euros, the sources said.

Two of the sources said none of the funds approached by Passera had committed to backing the fundraising.

"They are just open to the idea of doing a deal subject to due diligence," one source said. Another source said no deal was imminent. ($1 = 0.8951 euros) (Reporting by Pamela Barbaglia)